1. Field of the Invention
This invention relates to polysalt compositions and methods using the polysalt compositions for treating a waste system containing oil and water.
2. Brief Description of the Background Art
Industrial activities that require the use of process oils and water create waste systems that include oil and water. These industrial activities include but are not limited to, such as for example, the automotive industry, metal parts manufacturing and machining industries, steel mills, petroleum refining operations, adhesive industries, paint industries, textile manufacturing, paper industries, sewage treatment operations, and meat and food .processing plants. The mixture of the oil phase and the water phase in which either phase may be dispersed in the other is known by those skilled in the art as an emulsion. The type of oil found in the emulsion and the concentration of the oil will vary depending on the industry. For example, the oils may include animal, vegetable, mineral or synthetic oils. More specifically, these oils may include, for example, hydrocarbons such as tanins or greases, light hydrocarbons such as gasoline, lubricating oil, hydraulic pressure fluids, cutting oils, grinding fluids or animal processing oils. The concentration of the oil in the waste system may range, for example, from about 0.0001 to greater than 10% by volume.
It will be understood by those skilled in the art that the oil and water waste systems generated by industrial activity may include a wide range of various contaminants in addition to oil. Therefore, treatment of the waste system may include not only separation of the oil and water phases, but also removal of other contaminants.
A variety of chemicals have been proposed to separate a waste system into its oil and water components.
It is generally known by those skilled in the art that acids such as, for example, sulfuric acid, may be used to accomplish oil and water separation. Alternatively, polyvalent metal salts such as, for example, aluminum or iron salts are known to break oil and water emulsions. Although these acids and polyvalent, metal salts generally break oil and water emulsions, they have drawbacks, for example, the use of acids result in acidic waste water that requires neutralization, and polyvalent metal salts form high levels of hydroxide sludges that are difficult to dewater.
It is also generally well known by those skilled in the art that the use of high doses of organic cationic polymers are generally effective for separating oil and water. The organic cationic polymers include, for example, polyamines and poly dialkylammonium salts. However, these organic cationic polymers have the disadvantages of providing incomplete separations and forming moderate levels of sludge.
The use of liquid polysalts in acidic paper-making systems to improve the dry strength of paper is well known by those skilled in the arts of paper and pulp technologies. For example, U.S. Pat. No. 3,790,514 discloses a composition consisting essentially of an ionically self-crosslinked polysalt of a water soluble polyanionic polymer and a water soluble polycationic starch in a weight ratio between 95:5 and 5:95, and a water soluble ionization suppressor. This patent states that the polysalt compositions are used as strengthening agents for paper. This patent discloses that when the polysalts have reacted content of epichlorohydrin they have the property of imparting wet strength to paper in addition to dry strength. While the use of liquid polysalts, including for example polyanionic and polycationic starch compositions, have been used to enhance the dry and wet strengths of paper, no use has been made of polysalts of polyanionic and polycationic compositions for treating a waste system containing oil and water.
In spite of this background material, there remains a very real and substantial need for a polysalt composition capable of separating oil and water and an economical method for treating a waste system containing oil and water.